JP5962154B2 - Inkjet recording method and recording apparatus - Google Patents

Description

  The present invention relates to an ink jet recording method and a recording apparatus.

  Conventionally, various methods have been used as a recording method for forming an image on a recording medium based on an image data signal. Among these, the ink jet system is an inexpensive apparatus, and ink is ejected only to a required image portion to form an image directly on a recording medium. Therefore, the ink can be used efficiently, and the running cost is low. Furthermore, the inkjet method is excellent as a recording method because of its low noise.

  In recent years, in order to improve image quality, attention has been paid to a method of overprinting a colorless and transparent clear ink after printing a colored ink image.

  For example, Patent Document 1 discloses a method in which an ink set including color ink and clear ink containing a resin is prepared and printed on plain paper or high-quality paper by an inkjet method. In addition, it is also disclosed that the printing first prints color ink patches or images on the recording medium, then prints clear ink on the color ink printing area, and finally heats and dries it with a heater. (Specification paragraph 0067 of document 1).

JP 2010-221634 A

  However, as in the printing method disclosed in Patent Document 1, when the clear ink overcoating is performed (almost) simultaneously with the application of the color ink (colored ink), there is a problem that the glossiness is inferior. In addition, the ink disclosed in Patent Document 1 may be fixed in the vicinity of the ink jet head, which causes a problem that the clogging stability of the ink jet head is poor.

  Accordingly, an object of the present invention is to provide an ink jet recording method excellent in glossiness and clogging stability of an ink jet head.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] The inkjet recording method of this application example is an inkjet using at least a first ink composition containing a color material and a second ink composition containing a resin and substantially no color material. A recording method comprising: a first recording step of recording the first ink composition on a non-ink-absorbing or low-absorbing recording medium using an inkjet head to form an image; and an inkjet head. And a second recording step for recording the second ink composition on the image, and the first temperature is performed during the execution of the second recording step or after the second recording step. And a second drying step for drying the image, and a third drying step that is performed after the second drying step and dries the image at a second temperature that is a temperature exceeding the first temperature. Second ink composition Does not contain an aprotic polar solvent to substantially heat distortion temperature of the resin, characterized in that said first temperature exceeded is less than the second temperature.

  According to the ink jet recording method of this application example, the second ink composition is formed on the image of the first ink composition in the second recording step by drying the image formed by the second ink composition at the first temperature. Even when recording is performed, it is possible to ensure good ejection stability of the second ink composition and to obtain a recorded image of a clear image. Further, by performing the third drying step at a second temperature higher than the first temperature, it is possible to fix the image formed by the second ink composition. Since the second ink composition is a so-called clear ink composition that substantially does not contain a color material, the recorded surface has almost no rough surface or unevenness on the image surface due to drying at the second temperature, and has high glossiness. Can be obtained.

  Application Example 2 In the application example described above, the resin is one or more selected from an acrylic resin, a urethane resin, a polyester resin, and a styrene-acrylic resin.

  According to the application example described above, it is possible to form a recorded matter with excellent glossiness, and it is possible to obtain a recorded matter with higher abrasion resistance and excellent durability.

  Application Example 3 In the application example described above, the first recording step is performed while the recording medium is transported in the forward direction, and the second recording step is performed on the recording medium. It is performed while the transport operation in the reverse direction is performed, or while the transport operation in the forward direction is performed after the transport operation in the reverse direction is completed. .

  According to the application example described above, the inkjet head in the inkjet recording method, which is a recording means used in the recording process, and a heating device such as a heater as a drying means used in the drying process need not be provided for each recording process. Since the recording apparatus can be configured with the minimum number of heads and heating devices, a small recording apparatus can be obtained.

  Application Example 4 In the application example described above, the drying rate of the image formed in the first recording process before the second recording process is 60% or more.

  According to the above application example, the image formed by the first ink composition is dried at a first temperature to a drying rate of 60% or more, so that the second ink is formed on the image by the first ink in the second recording step. Even when recording with the composition is performed, the occurrence of bleeding between the image derived from the first ink composition and the second ink composition can be suppressed, and a recorded image with a clear image can be obtained.

  Application Example 5 In the application example described above, a first drying process is performed during the execution of the first recording process or before the second recording process, and the image is dried at a first temperature. In the second recording step, the second ink composition is recorded on the image formed in the first recording step, and after the second ink composition is dried on the recording medium, the second recording step is performed. And a step of recording the two-ink composition again.

  According to the above-described application example, the glossiness and the abrasion resistance are further improved by forming two or more layers of the second ink composition that does not substantially contain a color material, that is, a so-called clear ink composition. You can get things.

  Application Example 6 In the application example described above, the inkjet head used in the first recording step includes a nozzle array including a plurality of nozzle holes, and is scanned in a main scanning direction by a scanning mechanism. A first nozzle row in which a plurality of nozzle holes for discharging the first ink composition are arranged in a sub-scanning direction intersecting the main scanning direction, and a base ink composition for recording the base layer of the image is discharged. A plurality of nozzle holes arranged in the sub-scanning direction, and the first recording step moves the first nozzle row and the second nozzle row toward the sub-scanning direction. The base ink composition is recorded using the first group on the upstream side in the sub-scanning direction, divided into groups each including a predetermined number of the nozzle holes, and more than the first group. The sub-scanning method Using the second group downstream of, characterized by recording the first ink composition.

  According to the application example described above, it is possible to increase the recording speed by dividing the nozzle rows. In addition, by dividing the nozzle row, it is possible to eliminate the so-called back feed recording in which the recording medium is transported in a combination of the forward direction and the reverse direction, or to reduce the number of back feeds to a predetermined value. Records can be obtained.

  Application Example 7 A recording apparatus according to this application example is characterized in that an image is formed on the recording medium by the above-described ink jet recording method.

  According to the recording apparatus of this application example, it is possible to easily obtain a recorded matter that is small in size and excellent in glossiness and abrasion resistance.

1 is a block diagram illustrating a configuration of a printer according to a first embodiment. FIG. 2 is a schematic cross-sectional view around the head of the printer according to the first embodiment. FIG. 3 is a schematic diagram illustrating a recording unit that divides a nozzle row of the printer according to the first embodiment. The graph for calculating the drying rate in the 1st drying process. The list which shows the ink composition used for an Example. The table | surface which shows the result of redispersibility evaluation of the resin emulsion contained in a 2nd ink composition. The table | surface explaining the recording method in an Example. The table | surface which shows an Example. The graph which shows the glossiness in an Example.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary. In the present specification, the first ink composition and the second ink composition may be collectively referred to as an “ink composition”. In the present specification, “first temperature” and “second temperature” mean the temperature of the surface of the recording medium in contact with the ink composition. These temperatures can be measured using a commercially available thermographic apparatus. As a specific example of the thermography apparatus, there is an infrared thermography apparatus H2640 / H2630 [trade name] (manufactured by NEC Avio Infrared Technologies Co., Ltd.).

(First embodiment)
[Inkjet recording apparatus]
An ink jet recording apparatus according to the first embodiment of the present invention (hereinafter also simply referred to as “recording apparatus”) includes an ink jet head for discharging a first ink composition and an ink jet for discharging a second ink composition. There is no particular limitation as long as recording is performed by ejecting the ink composition from the head while moving the head (hereinafter also simply referred to as “head”) relative to the recording medium. Note that the head for ejecting the first ink composition and the head for ejecting the second ink composition may be different heads or the same head.

  As an example of the recording apparatus according to the present embodiment, an off-carriage type serial printer (hereinafter also simply referred to as “printer”) will be described with reference to the drawings. Here, the serial printer performs recording while the head moves back and forth in a direction intersecting the conveyance direction of the recording medium. Among these, an off-carriage type serial printer is a printer in which an ink cartridge containing an ink composition and a head on a carriage are connected by a tube. In the drawings used for the following description, the scale of each member is appropriately changed in order to make each member a recognizable size.

  FIG. 1 is a block diagram illustrating a configuration of the printer 1. FIG. 2 is a schematic cross-sectional view around the head of the printer 1. Here, the right and left direction (Y) of the paper surface shown in FIG. 2 corresponds to the direction (path) in which the recording medium is conveyed.

  The printer 1 according to this embodiment is directed to a non-ink-absorbing or low-absorbing recording medium P (hereinafter also simply referred to as “recording medium”) P, and the first ink composition and the second ink composition. Are ejected in this order to form an image on the recording medium P. Here, the printer 1 can form an image using ink compositions of various colors, and for printing using the first ink composition, for example, four color ink compositions of CMYK are used. For example, an image may be formed, or a white ink composition may be used to form a base that imparts excellent light shielding properties to the recording medium P. Examples of printing using the second ink composition include overcoating the first ink composition with a clear ink composition, thereby increasing glossiness.

  The printer 1 includes a transport unit 10, a carriage unit 20, a head unit 30, a heater unit 40, a detector group 50, and a controller 60. The printer 1 that has received print data from the computer 100, which is an external device, controls each unit (the conveyance unit 10, the carriage unit 20, the head unit 30, and the heater unit 40) by the controller 60. The controller 60 controls each unit based on the print data received from the computer 100 and forms an image on the recording medium P. The situation in the printer 1 is monitored by the detector group 50, and the detector group 50 outputs the detection result to the controller 60. The controller 60 controls each unit based on the detection result output from the detector group 50.

  The transport unit 10 is for transporting a recording medium P such as paper in a predetermined direction (hereinafter referred to as “transport direction” or “sub-scanning direction”). The transport unit 10 includes a paper feed roller 11, a transport motor (not shown), a transport roller 12, a platen 13, and a paper discharge roller 14. The paper feed roller 11 is a roller for feeding the recording medium P inserted into the paper insertion slot into the printer 1. The transport roller 12 is a roller that transports the recording medium P fed by the paper feed roller 11 to a printable area, and is driven by a transport motor. The platen 13 supports the recording medium P during printing, and the recording medium P is fed thereon by driving a paper feed motor (not shown). The paper discharge roller 14 is a roller for discharging the recording medium P to the outside of the printer, and is provided on the downstream side in the transport direction with respect to the printable area.

  The carriage unit 20 is configured to eject the ink composition onto the recording medium P with the head 31 stationary in the printing area while intersecting the transport direction (sub-scanning direction) (hereinafter referred to as “movement direction” or It is referred to as “main scanning direction”). The carriage unit 20 includes a carriage (not shown) and a carriage motor (not shown). The carriage has a head 31 therein and is connected to a carriage motor (not shown) via a timing belt (not shown). The ink cartridge (not shown) is placed at a different location from the carriage, and is stored in a cartridge storage portion (not shown) provided outside the printer 1 main body (outside the movement range of the carriage). Yes. An ink supply tube (not shown) is connected between the ink cartridge and the carriage. In this case, the ink cartridge and the carriage do not move together. Then, the carriage is reciprocated along the guide shaft by the carriage motor while being supported by a guide shaft that intersects the conveyance direction described later. The guide shaft is supported by a carriage that can reciprocate in the axial direction of the guide shaft.

  The head unit 30 is for ejecting the first ink composition and the second ink composition onto the recording medium P. The head unit 30 includes a head 31 having a plurality of nozzle holes. Since the head 31 is provided inside the carriage, when the carriage moves in the movement direction, the head 31 also moves in the movement direction. While the head 31 is moving in the moving direction, the first ink composition and the second ink composition are ejected onto the recording medium P. Thereby, a dot row along the moving direction is formed on the recording medium P. As described above, the head 31 ejects the first ink composition and the second ink composition onto the recording medium P, whereby the printer 1 as a recording apparatus can be simplified.

  The heater unit 40 includes heating means for drying and fixing an image formed by the ink composition ejected on the recording medium P. The heating means includes a drying heater 41 for heating to a first temperature at which the ink composition discharged and deposited (landed) on the recording medium P is dried at a predetermined drying rate, and a temperature higher than the first temperature and a first temperature. And a curing heater 42 for further heating and curing the image dried at one temperature and fixing the image on the recording medium P. Further, the fan unit 43 may be provided in the heater unit 40 for the purpose of promoting the drying of the image by the drying heater 41.

  The drying heater 41 is disposed on the downstream side in the transport direction (Y2 direction shown in FIG. 2) with respect to the head 31 and dries the image formed by the ink composition ejected from the head 31. A blower 43 is disposed adjacent to the drying heater 41. The curing heater 42 further dries and cures the image dried by the drying heater 41, and is disposed on the downstream side in the transport direction with respect to the drying heater 41.

  The detector group 50 includes a linear encoder, a rotary encoder, a paper detection sensor, an optical sensor, and the like. The linear encoder detects the position of the carriage in the moving direction. The rotary encoder detects the rotation amount of the transport roller 12. The paper detection sensor detects the position of the leading edge of the paper being fed (recording medium P). The optical sensor detects the presence or absence of the recording medium P by attaching a light emitting part and a light receiving part to the carriage. The optical sensor can detect the width of the recording medium P by detecting the position of the end of the recording medium P while moving by the carriage. In addition, the optical sensor is also referred to as the leading end (the end on the downstream side in the transport direction and also referred to as the upper end) and the rear end (the end on the upstream side in the transport direction and the lower end) depending on the situation. .) Can also be detected.

  The controller 60 is a control unit (control unit) for controlling the printer 1. The controller 60 includes a CPU 62 and a unit control circuit 64. The interface unit 61 transmits and receives data between the computer 100 which is an external device and the CPU 62. The CPU 62 is an arithmetic processing unit for controlling the entire printer 1. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and includes storage elements such as a RAM and an EEPROM. The CPU 62 controls each unit via the unit control circuit 64 in accordance with a program stored in the memory 63.

  When performing printing, the controller 60 alternately performs a dot forming operation for ejecting the ink composition from the head 31 moving in the moving direction and a transporting operation for transporting the recording medium P in the transport direction, as will be described later. Repeatedly, an image composed of a plurality of dots (including an overcoated image) is printed on the recording medium P. As described above, the ink jet recording apparatus using the ink composition forms an image (including an overcoated image) in a region facing the head 31 of the recording medium P.

[Modification of Inkjet Recording Device]
The above-described recording apparatus is an off-carriage type serial printer. Although not shown, when a large-capacity ink tank is added outside the printer 1, the large-capacity ink tank and the ink cartridge are connected by an ink supply tube. As a result, in the off-carriage type printer 1 as well as the on-carriage type printer, the storage amount of the ink composition can be greatly increased.

  The recording apparatus according to the present embodiment may be an on-carriage type serial printer in which an ink cartridge (ink tank) is mounted on a carriage together with the head 31. In the case of the on-carriage type, the carriage detachably holds an ink cartridge that contains an ink composition. In addition, the recording apparatus of the present embodiment may be a line printer that performs recording without moving the head substantially.

(Second Embodiment)
[Inkjet recording method]
The inkjet recording method according to the second embodiment (hereinafter also simply referred to as “recording method”) can perform recording using the inkjet recording apparatus 1 according to the first embodiment. The ink jet recording method according to the present embodiment includes at least the following first recording process and second recording process. In addition, the inkjet recording method according to the present embodiment includes a first drying step performed during the second recording step or after the second recording step, and a first temperature of the first drying step after the first drying step. It is preferable that the 2nd drying process performed at the 2nd temperature of the temperature over is included.

  Hereinafter, a recording method for conveying the recording medium P in the opposite direction to the conveyance path, that is, a recording method incorporating so-called back feed will be described with reference to FIG. 2, and each step in the inkjet recording method according to the second embodiment will be described. This will be described in detail. FIG. 2 is a schematic cross-sectional view of the ink jet recording apparatus 1 that executes the ink jet recording method incorporating back feed.

[First recording step]
In the first recording step, the head 31 is used to record the first ink composition on the non-ink-absorbing or low-absorbing recording medium P to form an image. In other words, an image made of the first ink composition is formed by ejecting and adhering (landing) the first ink composition from the head 31 toward the recording medium P. In the first recording process, images can be formed using ink compositions of various colors. For example, an image can be formed using a CMYK four-color ink composition, or a white ink composition can be used to form a base that provides excellent light-shielding properties to a recording medium. It is assumed that the first recording process is completed when the first ink composition ejected from the head 31 is formed (formed).

  Particularly in the case of a recording method incorporating back feed, as shown in FIG. 2, the first recording step is performed in the positive direction in the sub-scanning direction (Y direction in the figure) of the recording medium P, that is, from the upstream side in the transport direction. This is executed simultaneously with the carrying operation in the side direction (Y1 direction). In the first recording step, an image is formed by ejecting and landing the first ink composition from the nozzle holes in the head 31 toward the recording medium P in the main scanning direction that is substantially orthogonal to the sub-scanning direction. Is done. In this case, in the recording method using a serial printer, multi-pass printing with the number of passes (number of main scans) being two or more is possible. By forming the image by applying the ink composition in two or more times by this multi-pass printing, an image with further excellent image quality can be obtained.

[First drying step]
The ink jet recording method of the present embodiment further includes a first drying step. The first drying step may be performed by a plurality of drying means (heaters). The first drying process is performed while the first recording process is being performed or after the first recording process and before the second recording process, which will be described later, and a predetermined temperature (a plurality of temperatures may be used). The image may be dried at a first temperature or a second temperature described later). And it is preferable that the drying rate of the image formed by the said 1st recording process before the said 2nd recording process is 60% or more (it is preferable when the curing heater 42 is further used together). By setting the image drying rate to 60% or more before the second recording step, the layer formed from the second ink composition has high glossiness. Moreover, it is possible to prevent bleeding from occurring between the image derived from the first ink composition and the second ink composition. The drying rate is preferably 70% or more, and more preferably 80% or more in order to increase the glossiness of the image and to prevent the occurrence of bleeding more effectively.

  The “drying rate” in the present specification is the difference between the mass of the ink composition at the time of ejection and the mass of the ink composition after the drying, and the change in the mass of the ink composition at the time of ejection and the mass due to drying is substantial. It is calculated by dividing by the difference from the mass of the ink composition after drying at the point of time when it stopped. For example, the drying rate in the first drying step is measured and calculated as follows. The mass of the recording medium P when the first ink composition is applied to the recording medium P to form an image corresponds to a drying rate of 0%. Then, when the image is dried under predetermined drying conditions and the mass change of the recording medium P substantially stops, the drying rate corresponds to 100%. Using these two data and the mass data of the first ink composition at the time of recording the second ink composition, the drying rate can be calculated. FIG. 4 is described with reference to a graph showing a change with time of the drying rate when the drying time in the first drying step is changed.

  As described above, in the ink jet recording method according to the present embodiment, after the image obtained in the first recording step has a drying rate of 60% or more by the first drying step, the second recording step described later is performed. The first recording step and the second recording step are not performed (substantially) at the same time. Therefore, there is no problem that the ink composition bleeds, and the amount of ink composition to be applied is not particularly limited.

  Drying for making the drying rate of the image 60% or more (hereinafter also referred to as “drying with a drying rate of 60% or more”) is performed using at least the drying heater 41 (preferably, the curing heater 42 is used in combination). . As shown in FIG. 2, since the drying heater 41 is close to the head 31 from which the first ink composition is discharged, the discharge and drying of the first ink composition are performed (almost) simultaneously. In other words, the recording medium P does not move (substantially) in the sub-scanning direction while the first recording process and the first drying process are performed. Although it does not specifically limit as the drying heater 41, For example, an infrared heater, a warm air heater, and a hot air heater are mentioned. Among these, since only the recording medium P can be heated, an infrared heater that is extremely fast (high heating rate) is preferable. In the preferred first drying step, the drying rate of the image is set to 60% or more, so that the image can be dried at the first temperature and then further dried at the second temperature higher than the first temperature. In that case, it can carry out using the hardening heater 42 heated at 2nd temperature.

[Backfeed process]
In the back feed process, the recording medium P is transported in the reverse direction of the sub-scanning direction of the recording medium P, that is, in the direction from the downstream side to the upstream side in the transport direction (Y2 direction shown in FIG. 2). More specifically, the recording medium P obtained through the first recording step and the first drying step is conveyed in the Y1 direction shown in FIG. 2, and preferably in the Y1 direction up to the front of the curing heater 42. Then, the recording medium P is conveyed in the Y2 direction. In order to form a desired image, the ink composition is not ejected from the head 31 toward the recording medium P during the back feed process, and is transported downstream in the transport direction after the back feed process is completed. It is preferable to discharge the ink composition during the operation.

[Second recording step]
In the second recording step, the head 31 is used to discharge and record the second ink composition on the recording medium P with respect to the image dried in the first drying step. In other words, the second ink composition is ejected from the head 31 and attached (landed) toward the image formed by the colored ink composition in the first recording step, whereby the second ink composition becomes the colored ink composition. An overcoated image is formed on the formed image. As described above, the image in the present embodiment is formed in stages and is completed. Note that the second recording process is completed when the second ink composition ejected from the head 31 is formed (formed).

  In particular, in the case of a recording method including a back feed process, the second recording process is executed during the execution of the transport operation in the Y2 direction shown in FIG. 2 or after the transport operation in the Y2 direction is finished. In the second recording step, the top ink image is formed by ejecting and landing the second ink composition from the nozzle holes in the head 31 toward the image obtained in the first recording step in the main scanning direction. Further, the second recording step may perform recording using the second ink composition while transporting in the Y1 direction after finishing the transporting operation in the Y2 direction. Further, as shown in FIG. 2, the recording apparatus can be further downsized because the head 31 in the second recording step is the same as the head 31 in the first recording step. The head 31 in the first recording step and the head 31 in the second recording step may be different heads.

  By overcoating the second ink composition in the second recording step, it is possible to form a recorded matter (image) excellent in gloss and abrasion resistance of the recorded matter (image). Further, in order to further improve the gloss and abrasion resistance of the recorded matter (image), it is preferable to perform the recording operation in the second recording step twice or more. In other words, in the second recording step, the second ink composition is recorded (overcoated) on the image obtained in the first recording step, and the layer of the second ink composition (hereinafter referred to as “the second ink composition”) is recorded on the recording medium P. After the “clear ink layer” is dried, the second ink composition is preferably recorded (overcoated) again. In this case, it can be said that the second ink composition is applied twice. In addition, when the above-described overcoating is performed, the composition (type and content of compounding components) of the second ink composition constituting each clear ink layer may be the same or different.

[Second drying step]
The inkjet recording method of this embodiment further includes a second drying step. In the second drying step, the image formed in the second recording step is dried at the first temperature while the second recording step is being performed or after the second recording step. As described in the first drying step, the first temperature is preferably 40 ° C. or higher and lower than 70 ° C. from the viewpoint of ejection stability of the second ink composition. In the second drying step, when the image drying rate is 60% or more, the image can be dried at the first temperature and then further dried at a second temperature higher than the first temperature. In that case, it can carry out using the hardening heater 42 heated at 2nd temperature. In addition, when the image is dried using at least the drying heater 41 in the second drying step, the blower 43 may be used to promote the drying.

  The first temperature in the second drying step is at least lower than the thermal deformation temperature of the resin contained in the second ink composition, as will be described later. When the first temperature is lower than the thermal deformation temperature of the resin, the head 31 can be prevented from being damaged by heat. The specific temperature of the first temperature is preferably 40 to 60 ° C. in order to satisfy all the above conditions. Moreover, you may use the air blower 43 in order to accelerate | stimulate drying in a 2nd drying process. The blower 43 may supply either normal temperature air or cold air. The blower 43 is preferably arranged in the vicinity of the drying heater 41, that is, in the vicinity of the head 31.

  In the case of a recording method including a back feed process, in the second drying process, when the recording operation is performed twice or more in the second recording process, it is preferable to execute the second drying process after each recording process. Thereby, the glossiness and abrasion resistance of the recorded matter (image) can be further improved.

[Third drying step]
The ink jet recording method according to this embodiment preferably further includes a third drying step. The third drying step is performed after the second drying step. The third drying step is a drying step at the second temperature, and is preferably performed by the curing heater 42 set at the second temperature. As described above, the second temperature is set to be higher than the first temperature, and is set to a temperature at which the drying rate of the image formed by the second ink composition formed in the second recording step is further increased to be cured and fixed. The second temperature at which the drying rate in the third drying step is 70% or more is set, and as described later, at least the film forming temperature (MFT: Minimum Film Forming Temperature) of the resin contained in the second ink composition, or It is preferable that it is more than glass point transfer Tg. By setting the second temperature to MFT or Tg or higher, the above-mentioned resin melts and the rough feeling or unevenness of the top-coated image is eliminated (substantially), so that the glossiness is further improved. The specific temperature of the second temperature is preferably 70 ° C. or higher and 120 ° C. or lower, and more preferably 80 ° C. or higher and 110 ° C. or lower in order to satisfy all the above conditions. The above MFT will be described later.

  By including the back feed process, the inkjet recording apparatus 1 that performs the above processes periodically transports the recording medium P in the direction opposite to the transport path (Y1 direction shown in FIG. 2) (Y2 direction). Accordingly, since the number of heaters provided in the head 31 and the heater unit 40 can be minimized, the recording apparatus can be reduced in size.

[Modification of Inkjet Recording Method]
(1. Recording without backfeed)
As a modified example of the recording method of the present embodiment, instead of backfeed recording in which the recording medium P is conveyed in the direction opposite to the conveyance path of the recording medium P as described above, the recording medium P is stopped without being conveyed instead. For example, it may be left and dried by a drying heater 41 or natural drying.

(2. Recording by dividing nozzle rows)
As another modification example of the recording method of the present embodiment, the nozzle row may be divided and recorded by dividing the nozzle row into groups each including a predetermined number of nozzle holes. The ink jet head 31 used in the first recording process includes a nozzle row that is scanned in the main scanning direction by a scanning mechanism and includes a plurality of nozzle holes. The nozzle row includes a first nozzle row in which a plurality of nozzle holes for discharging the first ink composition are arranged in the sub-scanning direction intersecting the main scanning direction, and a base ink composition for recording the base layer of the image. And a second nozzle row in which a plurality of nozzle holes for discharging are arranged in the sub-scanning direction. At this time, in the first recording step, the first nozzle row and the second nozzle row are divided into groups each including a predetermined number of nozzle holes in the sub-scanning direction, and are located upstream in the sub-scanning direction. Recording by dividing the method of recording the base ink composition using the first group and recording the first ink composition using the second group located downstream of the first group in the sub-scanning direction. It's called a method. Hereinafter, this recording method will be described with reference to FIG. FIG. 3 is a schematic diagram showing a recording means by dividing nozzle rows.

  As shown in FIG. 3, the nozzle row 16 by the nozzle rows 16A and 16B in which the nozzle holes 17 are formed in the plurality of sub-scanning directions includes the first group on the upstream side T1 in the sub-scanning direction, and the sub-scanning direction. It is divided into the second group on the downstream side T2 in the scanning direction and used. First, while moving the carriage 4 in the main scanning direction (S1 and S2), droplets of the base ink composition are ejected from the first group of the first nozzle row 16A to form the base ink composition on the recording medium P. Of droplets. Next, the recording medium P is moved by the length of the first group in the sub-scanning direction in the downstream T2 direction in the sub-scanning direction. Then, while moving the carriage 4 in the main scanning direction, the first ink composition droplets are ejected from the second group of the second nozzle row 16B to form the first on the lower layer formed on the recording medium P. An image is obtained by depositing droplets of the ink composition. The same can be done when the nozzle row 16 is divided into three or more parts. The base ink composition is not particularly limited, and examples thereof include a white ink composition containing titanium dioxide and the like, and a glittering ink composition containing silver, aluminum and the like.

  The above-described recording method by dividing the nozzle rows 16A and 16B can increase the recording speed by dividing the nozzle rows 16A and 16B. Further, if the nozzle rows 16A and 16B are divided and used, the back feed of the recording medium P can be omitted or the number of back feeds of the recording medium P can be reduced. Thereby, it is possible to reduce the deviation of the printing position that may occur due to the back feed of the recording medium P. Further, as a preferred embodiment when using the base ink composition, the base ink composition and the first ink composition are applied by dividing the nozzle row to form an image, and the recording medium is transported downstream in the transport direction. Then, the image is dried by the heating mechanism on the downstream side. And the aspect which performs back feed after that and provides a 2nd ink composition is preferable.

(3. Recording with a line printer)
So far, recording methods and modifications have been described for recording by a serial printer. On the other hand, in the case of recording by a line printer, as many line heads as the number of types of ink compositions are required due to the structure of the printer. Therefore, for example, as described above, when the second ink composition is recorded twice (applied twice) to the image obtained in the first recording step, the line head for discharging the second ink composition Need two.

[Ink composition]
The ink composition described above (including the first ink composition and the second ink composition; the same applies hereinafter) is used in the ink jet recording method according to the above-described embodiment. The first ink composition contains a color material. The second ink composition contains a resin and does not substantially contain a coloring material. Here, “substantially does not contain” in the present specification means not to contain more than an amount that sufficiently exhibits the significance of addition. Quantitatively speaking, “substantially not containing” means that the content is 0.5% by mass or less with respect to the total mass (100% by mass) of the ink composition, preferably 0. .2% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, still more preferably 0.01% by mass or less. Hereinafter, additives (components) that are or can be included in the ink composition will be described.

[Color material]
The first ink composition contains a color material. As the color material, at least one of a pigment and a dye can be used.

(Pigment)
By using a pigment as the color material, the light resistance of the ink composition can be improved. As the pigment, either an inorganic pigment or an organic pigment can be used. As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, and titanium oxide can be used.

  Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes, chelate azo pigments, etc., phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Polycyclic pigments, dye chelates (eg basic dye chelates, acid dye chelates, etc.), dye rakes (basic dye rakes, acid dye rakes), nitro pigments, nitroso pigments, aniline black, daylight A fluorescent pigment is mentioned.

  More specifically, as a carbon black used for black ink, No. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (Mitsubishi Chemical (Mitsubishi Chemical Corporation), Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. Rega1 330R, Rega1 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. (Cabot Corp. CA Kol. , Color B lack FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color B1ack S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A , Special Black 4 (manufactured by Degussa).

  Examples of pigments used in white ink include C.I. I. Pigment white 6, 18, and 21.

  Examples of pigments used in yellow ink include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 167, 172, 180.

  Examples of pigments used in magenta ink include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, or C.I. I. Pigment violet 19, 23, 32, 33, 36, 38, 43, 50.

  Examples of pigments used for cyan ink include C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16, 18, 22, 25, 60, 65, 66, C.I. I. Bat Blue 4, 60.

  Examples of pigments other than magenta, cyan, and yellow include C.I. I. Pigment green 7,10, C.I. I. Pigment brown 3, 5, 25, 26, C.I. I. Pigment orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63.

  In addition, the said pigment may be used individually by 1 type, and may use 2 or more types together.

  When using said pigment, the average particle diameter has preferable 300 nm or less, and 50-200 nm is more preferable. When the average particle diameter is in the above range, the ink composition is more excellent in reliability such as ejection stability and dispersion stability, and an image with excellent image quality can be formed. Here, the average particle diameter in the present specification is measured by a dynamic light scattering method.

(dye)
A dye can be used as the coloring material. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9, 45, 249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food Black 1, 2, C.I. I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive black 3, 4, and 35 are mentioned.

  In addition, the said dye may be used individually by 1 type, and may use 2 or more types together.

  The content of the color material is preferably 1 to 20% by mass with respect to the total mass (100% by mass) of the ink composition because excellent concealability and color reproducibility can be obtained.

[Dispersant]
When the ink composition contains a pigment, it may further contain a dispersant in order to improve pigment dispersibility. Although it does not specifically limit as a dispersing agent, For example, the dispersing agent currently used for preparing pigment dispersion liquids, such as a polymer dispersing agent, is mentioned. Specific examples include polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, sulfur-containing polymers, fluorine-containing polymers, and epoxies. The thing which has 1 or more types of resin as a main component is mentioned. Commercially available polymer dispersants include Ajinomoto Fine Techno's Ajisper series, Solspers series (Solsperse 36000, etc.) available from Avecia and Noveon, and BYK Chemie's Dispersic series. , Disparon series manufactured by Enomoto Kasei.

〔resin〕
The 2nd ink composition in this embodiment contains resin (resin particle). When the second ink composition contains a resin, it is possible to mainly improve the abrasion resistance of the overcoated image.

  In addition, the 1st ink composition in this embodiment may contain resin. However, when the first ink composition does not contain a resin, the color material concentration of the first ink composition can be relatively increased, so that the image quality of the image can be maintained.

  Especially when performing the above-mentioned drying process, it is preferable that the heat distortion temperature of resin is 1st temperature or more and 2nd temperature or less. When the heat distortion temperature is equal to or higher than the first temperature, the clogging stability of the head 31 is further improved. On the other hand, when the thermal deformation temperature is equal to or lower than the second temperature, the resin melts and the surface of the topcoat image approaches smooth, so that the glossiness of the image is further improved.

  Here, the “thermal deformation temperature” in the present specification is a temperature value represented by a glass transition temperature (Tg) or a minimum film forming temperature (MFT). Among these, since MFT is easier to grasp the superiority or inferiority of the redispersibility of the resin than Tg, the thermal deformation temperature is preferably a temperature value represented by MFT. If the ink composition is excellent in resin redispersibility, the clogging stability of the head 31 is further improved because the ink composition does not adhere. The redispersibility evaluation method in the present specification employs the method described in the section of the examples. Moreover, Tg in this specification is described with the value measured by the differential scanning calorimetry. MFT in this specification is described by the value measured by ISO 2115: 1996 (title: plastic-polymer dispersion-measurement of white point temperature and minimum film forming temperature).

  The volume-based average particle diameter of the resin particles is preferably 50 to 200 nm. When the average particle diameter is within the above range, the gloss and the clogging stability of the head 31 can be further improved, and an overcoated image having a desired image quality can be formed over a long period of time.

  Examples of the resin include, but are not limited to, polyester resins such as aliphatic polyester resins and aromatic polyester resins, vinyl resins such as polyvinyl chloride resins, polyvinyl acetate resins, and polyvinyl alcohol resins, and vinyl chloride-vinyl acetate. Resins, ethylene-vinyl acetate resins, polyvinyl butyral resins, and cellulose resins such as ethyl cellulose resins, cellulose acetate propionate resins, and nitrocellulose resins, poly (meth) acrylic resins, poly (meth) acrylic acid methyl resins, and poly (Meth) acrylic resin such as (meth) ethyl acrylate resin, ethylene- (meth) acrylic resin, styrene- (meth) acrylic resin, ethylene- (meth) acrylic ester resin, urethane resin, polystyrene resin, Various resins such as carbonate resin, phenoxy resin, polyamide resin, polyimide resin, polysulfone resin, petroleum resin, chlorinated polypropylene resin, polyolefin resin, ethylene alkyl (meth) acrylate resin, rosin modified phenolic resin, NBR / SBR / MBR Examples thereof include synthetic rubbers and modified products thereof. When the resin is any of these components, the gloss and abrasion resistance of the overcoated image can be made excellent. Further, the clogging stability of the head can be made excellent, and an overcoated image excellent in image quality can be formed over a long period of time.

  Among these, since it is excellent in durability, at least one selected from an acrylic resin, a urethane resin, a polyester resin, and a styrene-acrylic resin is preferable.

  Among the resins, those capable of forming an emulsion are preferable. If a resin capable of forming an emulsion is selected, the second ink composition can be more effectively fixed on the image formed with the first ink composition by forming a film by drying.

  Among these, a water-based urethane resin emulsion is preferable. As this commercial item, for example, Movinyl 972 (solid content concentration 50%), 6530 (solid content concentration 44%), 742A (solid content concentration 46%) (Nippon Synthetic Chemical Industry Co., Ltd. .) Product name), Vinibrand 2500E (Nissin Chemical Industry CO., Ltd. product name, solid content concentration 35%), Superflex 110, 130, 170, 210, 300, 420, 420NS, 460, 470, 500, 610, 620, 650, 700, 740, 860, 870, E-2000, E-2500, E-4000, E-4800, R-5000 (above, Daiichi Kogyo Seiyaku (Dai -Ichi Kogyo Seiya u Co., Ltd. trade name), NeoRez R-9660, R-972, R-9637, R-967, R-940 (above, trade name made by KUSMOTO CHEMICALS), Adekabon Titers HUX-380, 401, 290K, 394, 680 (above, trade names made by ADEKA) and the like.

  The resin may be anionic, nonionic, or cationic. Among these, from the viewpoint of a material suitable for the head 31, nonionicity or anionicity is preferable. Moreover, resin may be used individually by 1 type and may be used in combination of 2 or more type.

  The content of the resin is preferably 1 to 30% by mass, and more preferably 5 to 10% by mass with respect to the total mass (100% by mass) of the second ink composition. When the content is within the above range, the gloss and rub resistance of the formed top coat image can be further improved.

[Surfactant]
The ink composition in the present embodiment may contain a surfactant. As the surfactant, an acetylene glycol surfactant or a polysiloxane surfactant is preferably used. The acetylene glycol surfactant or the polysiloxane surfactant improves the permeability of the ink composition by improving the affinity (wetting property) to the recording surface of the recording medium P. it can.

  Commercially available products can be used as the acetylene glycol surfactants, such as Olphine E1010, STG, Y (trade names manufactured by Nissin Chemical Industry Co., Ltd.), Surfynol. 104, 82, 465, 485, TG (the above-mentioned product name made by Air Products and Chemicals Inc.).

  Commercially available products can be used as the polysiloxane surfactant, and examples thereof include BYK-347 and BYK-348 (trade names manufactured by BYK).

  Furthermore, the ink composition may contain other surfactants such as an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant. Moreover, surfactant may be used individually by 1 type and may be used in combination of 2 or more type.

  The content of the surfactant is not particularly limited, but is preferably about 0.1 to 1.0% by mass with respect to the total mass (100% by mass) of the ink composition.

[Water-soluble organic solvent (wetting agent)]
In order to prevent clogging in the vicinity of the nozzle holes 17 of the head 31, the ink composition may contain a water-soluble organic solvent (wetting agent) that imparts a wetting effect. Examples of the wetting agent include, but are not limited to, for example, 1,2-hexanediol, glycerin, 1,2,6-hexanetriol, trimethylolpropane, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, Polyhydric alcohols such as tetraethylene glycol, pentaethylene glycol, dipropylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol , Glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol (sorbit), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose , So-called solid wetting agents such as sugar alcohols, hyaluronic acids, ureas, etc., C1-C4 alkyl alcohols such as ethanol, methanol, butanol, propanol, isopropanol, pyrrolidone carboxylic acid, aspartic acid, glycine, glycine, proline And so-called amino acids such as betaine, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, formamide, acetamide, dimethyl sulfoxide, sorbit, sorbitan, acetin, diacetin, triacetin, and And sulfolane.

  A water-soluble organic solvent may be used individually by 1 type, and may be used in combination of 2 or more type. In addition, in order to ensure proper physical properties (such as viscosity) of the ink composition and good printing quality and reliability, the content of the water-soluble organic solvent is based on the total mass (100% by mass) of the ink composition. About 5 to 30% by mass.

  Further, it is preferable that the first ink contains 0.5% by mass or more of 1,2-hexanediol, and the second ink contains substantially no 1,2-hexanediol. Although 1,2-hexanediol is a solvent that improves the ejection stability and the like, the reason is not clear, but when it is included in the second ink, there is a problem that the glossiness decreases. Occur. The reason is not clear, but 1,2-hexanediol may affect the dispersibility of the resin particles in the second ink.

[Aprotic polar solvent]
The second ink composition preferably contains substantially no aprotic polar solvent. This is because when the second ink composition does not substantially contain an aprotic polar solvent, the redispersibility of the resin contained in the second ink composition is improved and the ejection stability is excellent. On the other hand, it is preferable to add an aprotic polar solvent to the first ink composition depending on the type of the recording medium P. This is because when the first ink composition contains the aprotic polar solvent, the adhesion of the ink composition to the recording medium P such as vinyl chloride is further improved.

  Examples of the aprotic polar solvent include, but are not limited to, pyrrolidones, lactones, sulfoxides, imidazolidinones, sulfolanes, urea derivatives, dialkylamides, cyclic ethers, glycol diethers, and It is preferable to include one or more selected from the group consisting of amide ethers.

  Specific examples of the pyrrolidones include 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone. Specific examples of the lactones include γ-butyrolactone, γ-valerolactone, and ε-caprolactone. Specific examples of the sulfoxides include dimethyl sulfoxide and tetramethylene sulfoxide. Specific examples of the imidazolidinones include 1,3-dimethyl-2-imidazolidinone. Specific examples of the sulfolanes include sulfolane and dimethyl sulfolane. Specific examples of the urea derivative include dimethylurea and 1,1,3,3-tetramethylurea. Specific examples of the dialkylamides include dimethylformamide and dimethylacetamide. Specific examples of the cyclic ethers include 1,4-dioxane and tetrahydrofuran. Examples of the glycol diethers include diethylene glycol diethyl ether.

  Moreover, as said amide ether, the solvent shown by the following general formula (Formula 1) corresponds.

  In the formula, R 1 is preferably an alkyl group having 1 to 4 carbon atoms. The “C1-C4 alkyl group” may be a linear or branched alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, It may be an iso-butyl group, a sec-butyl group, or a tert-butyl group. The solvent represented by the formula in which R1 is an alkyl group having 1 to 4 carbon atoms can impart an appropriate pseudoplasticity to the ink composition, thereby ensuring good ejection stability of the ink. In addition, a solvent represented by the formula in which R1 is an alkyl group having 1 to 4 carbon atoms is preferable because the resin dissolving action is particularly strong.

The HLB value of the solvent represented by the formula is preferably 10.5 or more and 20.0 or less, more preferably 12.0 or more and 18.5 or less. When the HLB value of the solvent represented by the formula is within the above range, it is more preferable from the viewpoint of imparting appropriate pseudoplasticity to the ink and interaction with the resin component.
The HLB value of the solvent represented by the formula is expressed by the following formula from the ratio between the nonpolar value (I) and the organic value (O) in the organic conceptual diagram (hereinafter also simply referred to as “I / O value”). This is a calculated value.
HLB value = (Nonpolar value (I) / Organic value (O)) × 10
Specifically, the I / O values are as follows: “Systematic Organic Qualitative Analysis Mixture” (Fujita Kei, Kazama Shobo, 1974), “Dyeing Theory Chemistry” (Kuroki Nobuhiko, Tsuji Shoten, 1966), “ It can be calculated based on each document of “Organic Compound Separation Method” (Hiroo Inoue, Soukabo, 1990).

  When these aprotic polar solvents are included in the ink composition, an advantageous effect of improving the fixability to the recording medium can be obtained, and therefore, from the group consisting of pyrrolidones, lactones, sulfoxides, and amide ethers. One or more selected are more preferred.

〔water〕
The ink composition used in the ink jet recording method according to the above-described embodiment preferably contains water as a main solvent. Examples of this water include pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, and distilled water, or ultrapure water. Among these, water that has been sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be prevented and the ink composition can be stored for a long time.

[Other additives]
The ink composition in the present embodiment may contain additives other than the above (other additives). Examples of such additives include pH adjusters, preservatives, antifungal agents, penetration enhancers such as glycol ethers, and antioxidants.

The recording medium P used in the ink jet recording method of the above embodiment is a non-ink-absorbing or low-absorbing recording medium. This “non-ink-absorbing or low-absorbing recording medium” means a receiving medium that does not have an ink receiving layer (receiving layer) or has a thickness that does not sufficiently function as a receiving layer. A recording medium provided with a layer. More quantitatively, this “non-ink-absorbing or low-absorbing recording medium” means that the recording surface has a water absorption amount of 10 mL from the start of contact to 30 msec ^1/2 in the Bristow method. It means a recording medium that is / m ² or less.

The Bristow method described above is the standard number of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 "Paper and paperboard-Liquid absorbency test method-Bristow method". In short, the Bristow method is a method for measuring the wetting of the liquid on the surface of the recording medium in a short time in milliseconds and the subsequent penetration behavior of the liquid into the recording medium. Thus, the liquid is dynamically transferred to the test piece on the rotating wheel, and the absorption coefficient Ka [unit: mL / m ² · (msec ^1/2 )] is obtained from the absorption time and the transfer amount.

  The non-ink-absorbing recording medium P is not limited to the following. For example, a plastic film or paper that is not surface-treated for inkjet recording, that is, does not have an ink receiving layer, is made of plastic. Are coated and a plastic film is adhered. Examples of the plastic include, but are not limited to, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

  Examples of the recording medium P with low ink absorption include, but are not limited to, printing paper (recording paper) such as coated paper and fine coated paper, art paper, coated paper, matte paper, and cast paper. Can be mentioned.

  Coated paper refers to paper whose surface is coated with a paint to enhance aesthetics and smoothness. The paint can be prepared by mixing pigments such as talc, pyrophyllite, clay (kaolin), titanium oxide, magnesium carbonate, and calcium carbonate and an adhesive such as starch and polyvinyl alcohol. The coating is applied using a coater during the paper manufacturing process. There are two types of coaters: an on-machine type in which papermaking and coating are performed in one step by being directly connected to a paper machine, and an off-machine type in which papermaking is performed in a separate step.

The above-mentioned finely coated paper refers to a recording paper having a coating amount of paint of 12 g / m ² or less. The art paper mentioned above refers to a recording paper obtained by coating a high-quality paper (advanced recording paper) with a coating of about 40 g / m ² . The above coated paper refers to recording paper coated with 20g / m ² ~40g / m ² about paint. The above-mentioned cast paper refers to a recording paper that is finished so as to have better metallic gloss and smoothness by applying pressure to the surface of art paper or coated paper using a cast drum.

  By using the ink composition and the recording medium P described above, it is possible to provide an ink jet recording method excellent in glossiness and clogging stability of the head 31. More specifically, the glossiness of the clear ink coating film can be made excellent, and there is no possibility of bleeding, so that the amount of ink shot can be increased.

  Hereinafter, the embodiments of the present invention will be described more specifically by way of examples. However, the above-described embodiments are not limited only to these examples.

[Materials used]
The materials used in the following examples, comparative examples, reference examples, and experimental examples are as follows.
[Resin emulsion]
・ Movinyl 972 (Nippon Synthetic Chemicals product name, solid content concentration 50%)
・ Movinyl 6530 (Nippon Synthetic Chemicals product name, solid content concentration 44%)
・ Movinyl 742A (Nippon Synthetic Chemical Co., Ltd. trade name, solid content concentration 46%)
・ ViniBran 2500E (trade name, solid content concentration 35%, manufactured by Nissin Chemical Co., Ltd.)
[Pigment]
Carbon black (hereinafter also referred to as “K”)
Pigment Blue 15: 3 (hereinafter also referred to as “C”)
Pigment Red 122 (hereinafter also referred to as “M”)
Pigment Yellow 155 (hereinafter also referred to as “Y”)
(Water-soluble organic solvent)
1,2-hexanediol, 2-pyrrolidone (hereinafter also referred to as “2-P”)
Butylene glycol (hereinafter also referred to as “BG”)
[Surfactant]
・ BYK-348 (trade name manufactured by BYK)
〔water〕
·Pure water

[Preparation of pigment dispersion]
Here, the pigment was dispersed by the following method.
40 parts by mass of a dispersion resin (as a water-soluble resin, copolymerized at a mass ratio of methacrylic acid / butyl acrylate / styrene / hydroxyethyl acrylate = 25/50/15/10. Weight average molecular weight 12000) A water-soluble resin solution was prepared by charging into a mixed solution of parts by weight, 23 parts by weight of water, and 30 parts by weight of triethylene glycol-mono-n-butyl ether, and heating and stirring at 80 ° C to dissolve. To this solution (solid content 43%) 1.75 kg, the above pigments 3.0 kg, ethylene glycol 1.5 kg, and water 8.75 kg were blended and stirred with a mixing stirrer for premixing. This pigment mixture was dispersed by a multi-pass method using a horizontal bead mill with a multi-disk impeller having an effective volume of 1.5 liters and filled with 85% of 0.5 mm zirconia beads. . Specifically, the beads were mixed at a peripheral speed of 8 m / sec with a discharge rate of 30 liters per hour to obtain a pigment mixture.
Next, circulation dispersion was performed using a horizontal annular bead mill having an effective volume of 1.5 liters and filled with 95% of 0.05 mm zirconia beads. Use a screen with a pore diameter of 0.015 mm, disperse 10 kg of the pigment mixture at a circulation rate of 300 liters / hour for 4 hours at a bead peripheral speed of 10 m / second, and a pigment dispersion with a pigment solid content of 20%. Got.

[Preparation of ink composition]
Each material was mixed with the content shown in FIG. 5 and stirred at room temperature for 2 hours, and then filtered through a membrane filter having a pore size of 5 μm to obtain the first ink composition (Compositions 10 and 11) and Compositions 1 to 9 A second ink composition (clear ink composition) was prepared. Although the first ink composition is prepared in a plurality of colors, it has the same composition except that the pigment type is different (that is, only the pigment type of the compositions 10 and 11 is different from K, C, M, and Y. There are a total of eight types of first ink compositions). In addition, the unit of content shown in FIG. 5 is mass%. The solid content concentration of the resin in the clear ink composition was all 7%. Furthermore, the ink film-forming temperature in FIG. 5 corresponds to the MFT of the resin contained in the clear ink composition. Further, in the ink jet recording described later, each clear ink composition of each composition was formed at the corresponding ink film forming temperature in FIG.

  Here, since the redispersibility by the resin emulsion in each of the clear ink compositions represented by Composition 1 to Composition 8, that is, the redispersibility due to the difference in MFT of the resin, was evaluated, the results are summarized in FIG. The redispersibility is determined by visually observing whether or not each of the ink compositions 1 to 8 listed in FIG. 5 is dried at 50 ° C. for 1 hour and then re-dispersed with pure water. It was evaluated by. In FIG. 6, “◯” indicates that redistribution is performed, and “×” indicates that redistribution is not performed.

  When the ink composition has excellent redispersibility, the ink composition does not adhere to the ink composition, so that the head has excellent clogging stability, that is, the ink composition does not stably cause clogging of the head. From FIG. 6, the clear ink composition in which the solvent (water-soluble organic solvent) is butylene glycol (BG) and the MFT of the resin is 60 ° C. or higher is the mobile 972 or the mobile 6530 has excellent redispersibility. I understood.

  Next, the characteristics of the recorded matter depending on whether or not the aprotic polar solvent was contained in the first ink composition, that is, the color ink composition, were evaluated. The evaluation compositions are the composition 10 and the composition 11 shown in FIG. 5 which are color ink compositions, and the composition 10 contains 2-pyrrolidone, which is an aprotic polar solvent, and does not contain the composition 11. As an evaluation item, the abrasion resistance is evaluated, and the method is to set the recorded material after drying in a Gakushin type wear fastness tester AB-301 (trade name, manufactured by Tester Sangyo Co., Ltd.) and white cotton cloth at the contact portion. Rub 10 times with a friction piece (load: 300 g) attached (according to JIS L 0803), the color ink not transferred to the white cotton cloth was “◯”, and the transferred one was “X”. The results are shown in Table 1.

  As shown in Table 1, the color ink composition of composition 10 in which 2-pyrrolidone was added as an aprotic polar solvent to the color ink composition as the first ink composition was evaluated to have high abrasion resistance. Was obtained.

  Next, the characteristics of the recorded matter were evaluated depending on whether or not the clear ink composition as the second ink composition contained 1,2-hexanediol as a 1,2-alkanediol having 4 to 6 carbon atoms. The evaluation compositions are Composition 1 and Composition 9 shown in FIG. 5 which are clear ink compositions, and 1,2-hexanediol is included in Composition 9 but not in Composition 1. Glossiness was evaluated, and the average of 20 ° specular gloss on each color of KCMY was 60 or more, “◯”, and less than 60 was “x”.

  As shown in Table 2, the clear ink composition which does not contain 1,2-hexanediol in the clear ink composition which is the second ink composition was evaluated to have high glossiness.

  From the above evaluation results, in the examples shown below, the composition 10 shown in FIG. 5 is used as the color ink composition of the first ink composition, and the composition 1 and the composition 2 are used as the clear ink compositions of the second ink composition. Was used.

  Using IJ40 (polyvinyl chloride) manufactured by 3M as the recording medium, and using the colored ink composition of composition 10 and the clear ink composition of composition 2, and the ink jet recording apparatus shown in FIG. Thus, a recorded matter was produced.

[First recording step]
The first recording process was performed simultaneously with the carrying operation in the Y1 direction. In the main scanning direction, the colored ink composition was ejected and landed from the nozzle holes in the ink jet head toward the recording medium to form an image. The recording resolution was 720 × 1440 dpi, the number of scans was 10, the discharge weight per drop was 18 ng, and the duty was 100%.

[First drying step]
The first drying process was performed simultaneously with the first recording process. The image was dried at 60 ° C. using a drying heater 41 (infrared heater). The drying rate at this time was 85%. The drying rate was calculated based on the mass at the second recording step. Moreover, when drying the said image using the drying heater 41, the air blower 43 which supplies cold air was used.

[Backfeed process]
In the back feed process, the recording medium that passed through the first drying process was transported in the Y1 direction to the front of the curing heater 42, and then transported in the Y2 direction.

[Second recording step]
In the second recording step, the clear ink composition is ejected and landed from the nozzle row in the ink jet head (the same as in the first recording step) toward the image having a drying rate of 85%, thereby clear ink. An image (overcoated image) in which the composition was overcoated on the image was formed. The method for discharging the clear ink composition in the second recording step is summarized in the drawing. Method 1 in FIG. 7 is a method in which the clear ink composition is applied one layer at a time, and two layers are applied by two coatings. Method 2 is a method in which the clear ink composition is applied once for two layers. Method 3 is a method in which the clear ink composition is applied once for one layer.

[Second drying step]
The image was dried at 60 ° C. (first temperature) using a drying heater 41 (infrared heater). The drying rate at this time was 85%. The drying rate was calculated based on the mass at the second recording step. Moreover, when drying the said image using the drying heater 41, the air blower 43 which supplies cold air was used.

[Third drying step]
The third drying step was performed after the second drying step. The top coat image was dried at 100 ° C. (second temperature) using a curing heater 42 (infrared heater) and fixed on the recording medium. In this way, a recorded matter was obtained. In the coating method shown in FIG. 7, in Method 1, the second drying step was performed every time one layer was applied, and the third drying step was performed after the second second drying step.

  The composition 1 and composition 2 shown in FIG. 5 are used as the clear ink composition, the composition 10 shown in FIG. 5 is used as the color ink composition, and the recorded matter obtained by the above-described steps based on the recording method shown in FIG. The glossiness was evaluated. The glossiness was evaluated by measuring the 20 ° specular glossiness of the recorded material according to JIS Z8741: 1997, using a gloss meter (trade name “GlossMeter model number VGP5000” manufactured by Nippon Denshoku Industries Co., Ltd.).

  As a comparative control of Examples 1 to 4, a system in which the clear ink composition was not overcoated was used as an experimental example. The results of glossiness (20 degrees) in Examples 1 to 4 and the experimental examples are summarized in FIG. FIG. 9 is a graph showing the results of glossiness (20 degrees) in Examples 2 to 4 and Experimental Example 1. In Table 5 below, CMP corresponds to the creation of a black image using cyan ink (C), magenta ink (M), and yellow ink (Y).

  8 and 9, the glossiness of Example 1 and Example 2 is excellent, and in particular, the glossiness of Example 1 is excellent. That is, the two-layer two-time coating of the method 1 shown in FIG. 7 can obtain a glossiness superior to the two-layer one-time coating of the method 2 or the one-layer one-time coating of the method 3. Furthermore, even with the coating method of Method 1, the clear ink composition as the second ink composition obtained a result that the composition 2 shown in FIG.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 11 ... Paper feed roller, 12 ... Conveyance roller, 13 ... Platen, 14 ... Paper discharge roller, 31 ... Head, 41 ... Drying heater, 42 ... Curing heater, 43 ... Blower.

Claims (8)

An ink jet recording method using at least a first ink composition containing a color material and a second ink composition containing a resin and containing substantially no color material,
A first recording step of recording the first ink composition on a non-ink-absorbing or low-absorbing recording medium using an inkjet head to form an image;
A second recording step of recording the second ink composition on the image using an inkjet head, and
A second drying step that is performed during the execution of the second recording step or after the second recording step, and dries the image at a first temperature;
A third drying step, which is performed after the second drying step, and dries the image at a second temperature which is a temperature exceeding the first temperature.
Heat distortion temperature of the resin is, the first over-temperature, Ri said second temperature less than der,
An ink jet recording method , wherein a drying rate of the image during execution of the second recording step is 60% or more . The first ink composition contains 1% by mass or more of an aprotic polar solvent.
The inkjet recording method according to claim 1. The first ink composition contains 0.5% by mass or more of 1,2-hexanediol, and the second ink composition does not substantially contain 1,2-hexanediol.
The ink jet recording method according to claim 1, wherein the ink jet recording method is performed. The resin is at least one selected from an acrylic resin, a urethane resin, a polyester resin, and a styrene-acrylic resin.
The ink jet recording method according to claim 1, wherein the ink jet recording method is performed. During the execution of the first recording step or performed before the second recording step, of the preceding claims, and a first drying step of drying the image at a first temperature, characterized in including that The inkjet recording method as described in any one of Claims. In the second recording step, the second ink composition is recorded on the image formed in the first recording step, and after the second ink composition is dried on the recording medium, the second recording step is performed. 2 re-recording the ink composition;
The ink jet recording method according to claim 1, wherein the ink jet recording method is performed. The inkjet head used in the first recording step includes a nozzle row including a plurality of nozzle holes, and is scanned in the main scanning direction by a scanning mechanism.
The nozzle row includes a first nozzle row in which a plurality of nozzle holes for discharging the first ink composition are arranged in a sub-scanning direction intersecting the main scanning direction, and a base ink for recording a base layer of the image A second nozzle row in which a plurality of the nozzle holes for discharging the composition are arranged in the sub-scanning direction,
The first recording step includes
The first nozzle row and the second nozzle row are divided into groups each including a predetermined number of the nozzle holes in the sub-scanning direction.
Using the first group on the upstream side in the sub-scanning direction, the base ink composition is recorded, and using the second group on the downstream side in the sub-scanning direction with respect to the first group, Recording the first ink composition;
The ink jet recording method according to claim 1, wherein the ink jet recording method is performed. An image is formed on the recording medium by the ink jet recording method according to any one of claims 1 to 7.
A recording apparatus.

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